Generally, since a secondary battery may be charged and discharged unlike a primary battery, the secondary battery has been applied to various fields such as a digital camera, a cellular phone, a laptop computer, and a hybrid vehicle and has been actively studied. An example of the secondary battery includes a nickel-cadmium battery, a nickel-metal hydride battery, a nickel-hydrogen battery, and a lithium secondary battery. In addition, among these secondary batteries, the lithium secondary battery having a high energy density and a discharging voltage has been mainly studied, and has been commercialized and widely used.
Further, the secondary battery is configured in a form of a battery module in which a plurality of battery cells are stacked due to the necessity of a high output and a large capacity, and is configured of one battery pack by stacking and arranging a plurality of battery modules in parallel with each other and connecting positive electrode terminals and negative electrode terminals of neighboring battery modules to each other by bus bars.
Here, the bus bar has through-holes formed in both sides thereof, and the positive electrode terminal and the negative electrode terminal protruding outwardly of the battery modules are inserted into the through-holes and are fastened and are closely adhered and coupled thereto by a nut, thereby forming the battery pack in which the positive electrode terminal and the negative electrode terminal are electrically connected to each other.
However, when the battery modules are connected to each other by fastening the nut as described above, it is difficult to assemble the battery pack by stacking the battery modules or to perform disassembling and assembling at the time of maintenance due to abnormality of the battery pack.
As the related art, EP Patent Publication Application No. 2,337,119 entitled “Medium or Large Battery Pack Including Electrode Connection Device” has been disclosed.